Atomic Models
What was the key limitation of Rutherford’s atomic model?
It couldn’t explain why electrons don’t spiral into the nucleus due to electromagnetic attraction.
What is the Balmer series?
A set of spectral lines from hydrogen when electrons fall to the second energy level (n=2).
Who proposed the idea of matter waves?
Louis de Broglie.
What are the three types of radiation emitted during nuclear decay?
Alpha, beta, and gamma radiation.
What are the fundamental particles in the Standard Model?
Quarks, leptons, and gauge bosons.
How did Bohr’s model improve upon Rutherford’s?
Bohr introduced quantised energy levels for electrons, explaining atomic stability and spectral lines.
What does the equation E=hf represent in the context of hydrogen spectra?
It relates the energy of emitted photons to their frequency.
What is the de Broglie equation?
lamda = h/(mv)
Define half-life in terms of radioactive decay.
The time it takes for half of a radioactive sample to decay.
What are quarks and how do they combine to form hadrons?
Quarks are elementary particles; they combine in groups of 3 (baryons) or 2 (mesons) to form hadrons.
Why can't classical physics explain the stability of electron orbits?
Classical physics predicts electrons should lose energy and collapse into the nucleus, which doesn’t happen.
Use E=hc/λ to explain how energy relates to wavelength.
Energy is inversely proportional to wavelength; shorter wavelengths mean higher energy photons.
What does the de Broglie equation suggest about particles like electrons?
They have wave-like properties, with wavelength depending on momentum.
Which equation do you use to predict the number of radioactive particles remaining after a given time?
N_t = N_0 e ^(-lamda t)
What is the role of particle accelerators in physics research?
They collide particles at high energies to study subatomic structures and validate theories.
Describe one experimental observation that Bohr’s model could explain but Rutherford’s could not
The discrete line emission spectra of hydrogen.
What does the Rydberg formula calculate?
The wavelength of light emitted during electron transitions in hydrogen.
Describe one experiment that supports the existence of matter waves.
Electron diffraction through a crystal lattice.
The time it takes for half of a radioactive sample to decay.
Controlled fission regulates neutron release (e.g., reactors); uncontrolled leads to chain reactions (e.g., bombs)
Why are protons and neutrons not considered fundamental particles?
They are made of quarks, so they are composite particles.
Assess the limitations of both Rutherford and Bohr models in explaining atomic behaviour.
Rutherford’s model lacked electron stability; Bohr’s model couldn’t explain spectra of multi-electron atoms or electron wave behaviour.
Calculate the wavelength of light emitted when an electron falls from ni=3 to nf=2 in hydrogen.
656 nm
How did de Broglie’s theory contribute to the development of quantum mechanics?
It introduced wave-particle duality, leading to Schrödinger’s wave equation and modern atomic theory.
Calculate the energy released using E=mc2 given a mass defect of 0.002 kg.
1.8 x 1014 J
Describe the four fundamental forces and their role in particle interactions.
Gravity (attraction between masses), electromagnetic (attraction between charges), strong nuclear (binds quarks), and weak nuclear (responsible for decay).